In which of the following , the double bond consists of both pi bonds

Options

A. `O_(2)`
B. `C_(2)`
C. `Be_(2)`
D. `S_(2)`.

Answer

To determine which of the given options has a double bond consisting of both pi bonds, we need to analyze each option one by one.

### Step-by-Step Solution:

1. **Analyze the first option: O2 (Oxygen)**
- The molecular structure of O2 is represented as O=O.
- In O2, there is one sigma bond and one pi bond.
- Therefore, O2 does not have a double bond consisting of both pi bonds.

2. **Analyze the second option: C2 (Dicarbon)**
- The molecular structure of C2 is represented as C≡C (a triple bond).
- In C2, there is one sigma bond and two pi bonds.
- Thus, C2 does not have a double bond; instead, it has a triple bond.

3. **Analyze the third option: B2 (Diboron)**
- The molecular structure of B2 is represented as B-B.
- In B2, there is one sigma bond and no pi bonds.
- Therefore, B2 does not have any double bond.

4. **Analyze the fourth option: Boron (Atomic form)**
- In its atomic form, boron does not bond with itself or any other atom.
- Hence, there are no sigma or pi bonds present in atomic boron.
- Therefore, boron does not have any double bond.

5. **Conclusion:**
- After analyzing all options, we find that none of the options have a double bond consisting of both pi bonds. However, if we consider the question's phrasing, the closest option that involves pi bonds is C2, which has two pi bonds in a triple bond configuration.

### Final Answer:
The correct answer is option C2, but it is important to note that C2 has a triple bond, not a double bond.